21385944 has 112 divisors (see below), whose sum is σ = 63612600. Its totient is φ = 6718464.

The previous prime is 21385937. The next prime is 21385951. The reversal of 21385944 is 44958312.

It is an interprime number because it is at equal distance from previous prime (21385937) and next prime (21385951).

It is a super-2 number, since 2×21385944² = 914717201542272, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 21385899 and 21385908.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 27 ways as a sum of consecutive naturals, for example, 110712 + ... + 110904.

Almost surely, 2^21385944 is an apocalyptic number.

21385944 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21385944, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31806300).

21385944 is an abundant number, since it is smaller than the sum of its proper divisors (42226656).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21385944 is a wasteful number, since it uses less digits than its factorization.

21385944 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 236 (or 217 counting only the distinct ones).

The product of its digits is 34560, while the sum is 36.

The square root of 21385944 is about 4624.4939182574. The cubic root of 21385944 is about 277.5723113234.

The spelling of 21385944 in words is "twenty-one million, three hundred eighty-five thousand, nine hundred forty-four".